11 Proximal Opening Wedge First Metatarsal Osteotomy for Hallux Valgus Correction Abstract Proximal opening wedge osteotomy of the first metatarsal is a reasonable treatment option for patients with symptomatic hallux valgus. Patient demographics, degree of symptoms, and the severity of the deformity should all be used to determine whether a proximal opening wedge osteotomy best suits a certain patient. This chapter provides a brief overview of the indications and contraindications for performing a proximal opening wedge osteotomy. In addition, the chapter contains a detailed preoperative planning guide, step-by-step operative technique, and potential risks or hazards that one might face intraoperatively. Expert advice and techniques are divulged to help avoid these hazards and minimize the risk for common postoperative complications. Overall, high patient satisfaction scores and equal results have been shown between proximal first metatarsal opening wedge osteotomy and alternative surgical options for patients suffering from hallux valgus. Keywords: proximal metatarsal osteotomy, opening wedge osteotomy, hallux valgus • Utilization of proximal opening wedge osteotomy with exostosis for correction of hallux valgus first described by Trethowan in 1923 and Trott in 1972.1,2 • Historically utilized in adolescent hallux valgus.3 • Subsequent abandonment of procedure occurred with concerns for stability, dorsal malunion, and transfer metatarsalgia.4 • Patients with moderate or severe hallux valgus, which is symptomatic (i.e., pain in and out of shoe wear or limitations in reasonable shoe wear)5,6 (Fig. 11.1). • Patients having previous osteotomy with subsequent shortening of the first metatarsal.7 • Perform a complete neurovascular examination of the foot. • Assess the range of motion of the first metatarsal-medial cuneiform joint. • Assess the range of motion of the first metatarsal phalangeal joint (hypermobility or severe limitation of motion contraindication for procedure). • Assess the pronation component to the deformity—if no pronation component is involved, deformity cannot be corrected with a proximal metatarsal osteotomy. • Measurements must be evaluated from weight-bearing radiographs of the foot (Fig. 11.2). • Hallux valgus angle (HVA) > 30 degrees.6 • Intermetatarsal angle (IMA) > 13 degrees.6 • Normal to slightly elevated distal metatarsal articular angle (DMAA), normal being < 10 degrees. • Accommodative shoe wear. • Shoes with < 1-inch heel to avoid progression of deformity. • Insertion of toe spacer. • No role for custom orthotic management. • No role for steroid injection therapy. • No role for physical therapy. • Hypermobility or instability of the first tarsometatarsal (TMT) joint may have independent causation of increased IMA, one that will not be corrected with proximal metatarsal osteotomy. These patients may be treated more appropriately with a first metatarsal-medial cuneiform arthrodesis (Lapidus’ procedure).5,6 Fig. 11.2 Weight-bearing radiograph of patient demonstrating increased HVA and IMA angles. • Rotational deformities of the first metatarsal.5 • Anatomically narrow first metatarsal—due to the difficulty for obtaining stable fixation.6 • Severe arthritis of the metatarsophalangeal (MTP) joint.3,6 • Relative contraindication for severely osteoporotic patients.6 • Longer first metatarsal compared to the second metatarsal.3 • Large DMAA—due to further increase in DMAA with rotational component of osteotomy.3 • History of first metatarsal infection. • Avascular necrosis of the first metatarsal. • Relieve pain and discomfort. • Restore the physiologic function of the first ray and alignment of great toe.5 • Correction of hallux primus varus. • Decrease IMA between first and second metatarsals. • Preserve length of the first metatarsal. • Ability to achieve a large correction of hallux primus varus without compromising length of first metatarsal. • Less technically demanding and more straightforward of a procedure compared to proximal chevron osteotomy or biplanar osteotomy.1 • Low rates of nonunions.5 • Low rates of healing complications due to minimal periosteal stripping and intact lateral cortex. • Rapid incorporation of selected bone graft supplement, if utilized. • Decreased risk of hardware complications with new and improved fixation techniques. • Less deviation against the mean absolute Meary’s angle compared to proximal chevron osteotomy.1 • Step #1: perform distal soft-tissue procedure.8 • Step #2: excise the medial eminence of the first metatarsal. • Step #3: perform proximal opening wedge osteotomy. • Step #4: plication of medial MTP joint capsule. • Position patient supine and consider use of thigh or calf tourniquet.6 • Consider the use of a small hip bolster to provide neutralization of the lower extremity and minimize amount of external rotation. • Consider the administration of regional anesthesia or nerve block for optimal postoperative pain control.4,6 • Utilizing fluoroscopy and direct visualization, identify the location of the first TMT joint. • Make a 2to 3-cm medial longitudinal incision from the first metatarsal-medial cuneiform articulation, extending distally (Fig. 11.3a,b). • Measure 1.5 cm distal to the first TMT joint, and mark site for correct osteotomy placement. • Perform a transverse or oblique osteotomy. • Maintain lateral cortex intact to serve as a hinge.1 • Open the osteotomy site.1 • Utilize fluoroscopy with different size wedges until achieving appropriate correction to the IMA (each 1 mm of wedge provides 3 degrees of correction).1 • Fixation of wedge plate onto the medial aspect of the metatarsal to maintain opening wedge.1 • Secure the plate with two distal and two proximal screws (paying close attention to not violate the TMT joint)1 (Fig. 11.4). • Insert the appropriate amount of bone graft into the osteotomy site from excised medial eminence or additional distal tibia harvest or autograft1 (Fig. 11.5). • Close tissue deeply over plate construct to decrease edema. • Approximate skin edges of medial incision and recommend the use of interrupted simple sutures with nylon for closure (Fig. 11.6).
11.1 Introduction
11.2 Indications
11.2.1 Clinical Evaluation
11.2.2 Radiographic Evaluation
11.2.3 Nonoperative Options
11.2.4 Contraindications
11.3 Goals of Surgical Procedure
11.4 Advantages of Surgical Procedure
11.5 Key Principles
11.6 Preoperative Preparation and Positioning
11.7 Operative Technique
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